Photographic background device

ABSTRACT

A photographic background device enables a photographer to include a scene reproduced on a film transparency as background for photographed subjects. A transparency is illuminated while a beam splitter mirror directs light from the illuminated transparency to the camera lens, while allowing light from the subject to pass through the mirror to the camera lens. A movable lens system of positive power is provided to allow the transparency image to appear in focus at the lens. Vignetting is alleviated by locating a concave mirror on the side of the beam splitter opposite the side on which the movable lens system is located. In this manner, the illuminated film transparency image will pass through the beam splitter, be reflected by the concave mirror back to the beam splitter and be reflected from the beam splitter to the camera lens.

BACKGROUND OF THE INVENTION

This invention relates to an improved system for providing aphotographed subject with selected backgrounds, and more particularly,to a system in which a device is mountable directly to a camera wherebya subject may be photographed with a desired background not requiringthe use of painted backdrops, rear projection screens, front projectionscreens, or the like.

Selection of photographic backgrounds is very important to thephotographer, particularly to the commercial portrait photographer whomust rely on such backgrounds to make his work consistently interestingand appealing to the eye. Selected photographic techniques have beenheretofore used to eliminate or minimize the intrusion of anobjectionable background in a photograph. One such technique involvesshooting at as wide open a lens aperture as is practicable. In thismanner, the depth of field of lens used is minimized and the backgroundwill appear to be an indistinguishable blur, when the subject is infocus. Such techniques, however, add nothing to overcome the problem ofincluding an otherwise undistinguishable background as part of thefinished pictures.

The use of a painted backdrop is as old as the art of commercialphotography itself, to which countless tintypes and daguerretypes willattest. Such backdrops are, of necessity, limited in subject matter,difficult to create and maintain, cumbersome to erect and burdensome tocarry. Thus the photographer was fairly restricted to the confines ofhis own studio, and likewise limited in the number of availablebackdrops he could offer to his clients.

A more recent innovation has been the use of photographic screens ontowhich transparencies may be projected to produce a desired background.One such projection technique involves a translucent screen and a slideprojector mounted at its rear. The image thus appears on the screen'sfront surface. With the slide so projected, the subject stands in frontof the screen and the photographer proceeds conventionally with hisshooting.

While offering a somewhat more portable and flexible backdrop system,the rear projection approach requires erection of a screen, positioningof the projector at a distance behind the screen sufficient to enablethe projected image to fill the screen, sources of electrical power tooperate the projector, and elaborate and carefully controlled frontlighting techniques to illuminate the subject without "washing out" theprojected image.

A variation of this technique involves front projecting an image onto ascreen through a beam splitter mirror which directs the reflected screenimage back to a camera. The subject to be photographed is positionedcoaxially with the lens of the camera at a position beyond the beamsplitter. Such an apparatus is described in U.S. Pat. No. 3,366,438issued to H. W. Hartman.

A variation of this procedure may be seen in U.S. Pat. No. 3,920,320issued to Ellis and Ryan, where the transparency projector, the beamsplitting mirror and the camera have been combined on a single chassis.

As is evident from a reading of both patents, a projection screen isstill required and care must be taken in lighting and in projecting theimage onto the screen to assure that shadows from the subject positionedbefore the screen will not intrude onto the projected backdrop.

Problems are also encountered in adequately lighting the subject whilemaintaining the sharpness and clarity of the projected background. Itmay also be seen that, while the two patents discussed above offer somesignificant advantages, the portability and ease of use of eachdescribed apparatus is somewhat limited due to the cumbersome equipmentlighting and projection screen involved.

A somewhat more compact attachment, for causing a grid or other desiredreference pattern to be projected onto the film in the camera and alsoonto the viewing screen of the camera's viewfinder, at the same timethat a subject is being photographed by the camera, is disclosed inFaasch U.S. Pat. No. 3,376,800. Faasch discloses a beam splitter mirrorfor reflecting a transparency image to the camera lens and for allowingthe subject to simultaneously be photographed through the beam splitter.We have discovered, however, that when a beam splitter mirror isinterposed between the camera lens and a lens for focusing atransparency image, vignetting may occur. We have also discovered anovel system for alleviating such vignetting, by effectively focusingthe entrance pupil of the camera lens approximate the exit pupil of thelens which focuses the transparency image.

Therefore, it is an object of the present invention to provide simpleapparatus for combining selected film transparencies as backgrounds withsubjects to be photographed, with the problem of vignetting beingalleviated.

Other objects and advantages of the present invention will becomeapparent as the description proceeds.

SUMMARY OF THE INVENTION

In accordance with the present invention, apparatus is disclosed forproviding a photographed subject with selected backgrounds, with thebackgrounds being maintained on film transparencies. The apparatus hasone portion thereof positionable adjacent a camera lens, means forholding a film transparency, means for illuminating the filmtransparency, beam splitter means, optical focusing means locatedbetween the film transparency and the beam splitter means, with theilluminating means being located on the side of the film transparencyopposite the side on which the focusing means is located.

The improvement comprises a concave mirror located on the side of thebeam splitter means opposite the side on which the optical focusingmeans is located. The beam splitter means has a partially reflectivemirror surface and the beam splitter means is positioned to permit theilluminated film transparency image to pass through the beam splittermeans, be reflected by the concave mirror back to the beam splittermeans and be reflected from the beam splitter means to the camera lens.The concave mirror is operative to focus the entrance pupil of thecamera lens approximate the exit pupil of the optical focusing means.

In the illustrative embodiment, the beam splitter means comprises a beamsplitter cube in which the diagonal thereof is light-transmissive with apartially reflecting mirror surface. The optical focusing meanscomprises a first cylindrical lens for reducing astigmatism and amovable lens system of positive power. The beam splitter means is angledat a 45° angle with respect to the lens axis and extends from below thecamera lens and upwardly and away therefrom.

A more detailed explanation of the invention is provided in thefollowing description and claims, and is illustrated in the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a photographic background deviceconstructed in accordance with the principles of the present invention;

FIG. 2 is a cross-sectional view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a schematic representation illustrating one technique of useof the device of FIG. 1;

FIG. 5 is a representation of a completed photograph using thearrangement in FIG. 4;

FIG. 6 is a schematic view of a background photographic deviceconstructed in accordance with the FIG. 2 embodiment of the presentinvention;

FIG. 7 is a schematic view of a photographic background device accordingto a modified form of the invention;

FIG. 8 is a schematic view of a photographic background device accordingto a further modified form of the invention;

FIG. 9 is a schematic view of a photographic background device accordingto another modified form of the invention; and

FIG. 10 is a schematic view of the FIG. 9 embodiment, for the purpose ofshowing an illustrative example of operable dimensions.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS

Referring to the drawings, a photographic background apparatus 10 has ahollow housing 11 with slide retainer 14 and illumination base 12positioned at one end. The illumination base 12 may contain anelectronic flash which is synchronized with the shutter of a camera, asillustrated in FIG. 4, or it may contain a battery or householdcurrent-operated incandescent lamp 18, as illustrated in FIG. 2.

Apparatus 10 includes a mirror support housing 26, one end 28 of whichfaces the camera lens 30 of a camera 31 and the other end 34 of which isadapted to be aimed toward the subject whose photograph is being taken.

Housing 26 includes a sleeve 33 which is adapted for coupling to thecamera lens 30. The housing also includes a beam splitter mirror 40,which is positioned at a 45° angle with respect to the axis 42 of thelens 30 and extends upwardly and outwardly from the bottom plane of lens30 to the top plane thereof. Beam splitter mirror 40 islight-transmissive, preferably transparent, with a partially reflectingmirror surface. If desired, the beam splitting device may comprise abeam splitter cube in which member 40, which forms the diagonal of thecube, is light-transmissive with a partially reflecting mirror surface.

Housing 11 is provided with a slot 14 for receiving a transparency 15.Transparency 15 is used to provide a background image 16, whenilluminated by lamp 18, as is described below.

A movable optical focusing means 44 is provided between the beamsplitter 40 and the transparency 15. Optical focusing means 44preferably comprises a movable lens system 46 of positive power. Lenssystem 46 may comprise a single convex lens as illustrated in FIG. 2, ormay comprise a complex lens forming a positive power element. Lens 46 ismounted within a carrier 48 to which lugs 20 are connected forpermitting the carrier 48 to be moved within slot 21 defined by housing11.

In order to permit access to lamp housing 12, housing 11 may bethreadedly connected to the lamp housing 12 so that by unscrewing thehousing 11 from the lamp housing 12 the disconnection can be made andaccess may be permitted within the lamp housing 12. For simplicity inconstruction, mirror housing 26 is preferably formed as a generallycylindrical construction and is fastened to housing 11 substantially asillustrated in FIGS. 1 and 3.

In order to alleviate vignetting, a concave mirror 50 is provided on theside of beam splitter 40 opposite the side on which focusing means 44 islocated. Concave mirror 50 may take the form either of a front surfacemirror, in which the reflecting surface is immediately accessed by thelight from the transparency 15, or a rear surface mirror in which theconcave reflecting surface is accessed only after the light from thetransparency 15 has been refracted at an entrance face and has traverseda path in either glass or transparent plastic. The use of transparentplastic for the concave rear surface mirror is preferred for a low costapplication, and is characterized by the fact that the entrance facereferred to is substantially of planar form (see FIG. 7).

Concave mirror 50 is used to focus the entrance pupil of the camera lensin or near the exit pupil of lens system 46. The optical power of lenssystem 46 is such that when it is taken in conjunction with the opticalpower of concave mirror 50, the light from the transparency 15 after itsreflection by the beam splitter 40, is brought to a common focus on thefilm plane of the camera as light which comes from the subject traversesthe beam splitter 40 without reflection. Thus the image of the subjectwill pass to lens 30 through beam splitter 40 without reflection. Theimage of transparency 15 will be focused by lens system 46 and will passthrough beam splitter 40 to concave mirror 50, be reflected back to beamsplitter 40 and be reflected from beam splitter 40 to lens 30. Byfocusing the entrance pupil of the camera lens approximate the exitpupil of focusing lens 46, vignetting is alleviated.

A schematic representation of one embodiment of the invention isillustrated in FIG. 6, in which a beam splitter cube 40' has atransparent diagonal member 40 with a partially reflecting mirrorsurface. Beam splitter cube 40 is positioned between lens 30 andfocusing lens 46 and concave mirror 50 is located on the side of beamsplitter cube 40' opposite to the side on which focusing lens 46 islocated. The image of subject 36 will pass through beam splitter 40,without reflection, to lens 30. The image of transparency 15, whenilluminated, will pass through beam splitter 40, without reflection, andthen be reflected back to beam splitter 40 by concave mirror 50 andthereupon be reflected to lens 30.

The embodiment of FIG. 7 is similar to the FIG. 6 embodiment, exceptthat concave mirror 50' comprises a lens/mirror system having a planarbottom surface 52 and its top surface 54 having a reflective material,such as aluminum, deposited thereon. The apparatus of FIG. 7 operatessimilarly to the FIG. 6 apparatus, except that the concave reflectingsurface 54 of concave mirror 50' is accessed only after the light fromthe transparency has been refracted at entrance face 52.

FIGS. 8 and 9 show a system in which light housing 12, transparency 15and focusing means 46 extend horizontally. To this end, a mirror 60 isprovided for reflecting the transparency image upwardly and through beamsplitter 40, to concave mirror 50 where it is reflected back to beamsplitter 40 and thereupon reflected to lens 30. In the FIGS. 8 and 9embodiment, the optical focusing means includes a complex lens system 46of positive power and a cylindrical lens 62 for reducing astigmatism.Lens 46 is actually movable to focus the transparency image.

The FIGS. 8 and 9 embodiments are similar, except that in the FIG. 8embodiment, a concave mirror 50 is used for reflecting the transparencyimage back to beam splitter 40, while in the FIG. 9 embodiment, aconcave mirror/lens system 50' is utilized. Concave mirror/lens system50' has a generally planar bottom surface 52 and a mirrored top surface54 upon which aluminum or the like is deposited, in the manner asdescribed with respect to concave mirror/lens system 50' of the FIG. 7embodiment.

In the FIGS. 8 and 9 embodiments, an intermediate image 64 is formedbetween mirror 60 and beam splitter 40, as illustrated. If desired, aground glass member may be provided between mirror 60 and beam splitter40 to receive the intermediate image 64.

Cylindrical lens 62 is optional and for highest quality it is useful inconnection with a complex lens system 46 for reducing astigmatism.Although no limitation is intended, as a specific example a 25 wattillumination lamp 18 may be utilized and for most accurate resultsshould be color corrected by means of filters or the like. The cameralens aperture should be set at F/2.8 or F/4. Mirror 50 may have a radiusof curvature of 9.414 inches and, if a glass type, have a refractiveindex of 1.523 and a dispersion of 59.5 (Abbe No.). Lens 50' may have athickness of 0.6 inch and have a clear aperture of 3 inches by 4 inches.

Beam splitter 40 may be a 4.25 inch×4.25 inch cube with the glassforming the beam splitter being 0.062 inch thick. Mirror 60 may besquare having a 3 inch by 3 inch dimension and a thickness of 1/8 inch.Relay lens 46 may be a 2 inch F/1.9 lens or a 2 inch F/2 lens.

Illustrative dimensions between the parts, with reference to the diagramof FIG. 10, are as follows:

    ______________________________________                                        Spacing          Distance In Inches                                           ______________________________________                                        AB               3.0                                                          BC               1.5                                                          BD               2.75                                                         DE               3.75                                                         EF               3.25                                                         ______________________________________                                    

In utilizing the apparatus disclosed, with reference to FIG. 4 a subject36 is placed adjacent a dark background 39, preferably a blackbackground. Subject 36 is illuminated by means of natural illuminationor photographic lamp 37. The device is attached to the camera lens asillustrated and transparency 15 having a desired background 16 thereonis inserted into slot 14. If the illumination housing 12 contains anelectronic flash, the electronic flash is energized for synchronizationwith the camera shutter. The lens of the camera is adjusted to focusupon the subject 36 and lugs 20 are moved so that the transparencypicture 16 will be focused by lens system 46 with respect to the cameralens.

If an electronic flash is utilized, the electronic flash is energized byswitch 35 for synchronization with the camera shutter. When the camerashutter is actuated, the image of the subject will pass through beamsplitter 40, without reflection, to camera lens 30. Simultaneously theimage of background 16 will pass through beam splitter 40, withoutreflection, to concave mirror 50, be reflected back to beam splitter 40and be reflected from beam splitter 40 to lens 30.

It can be seen that a simple apparatus has been provided for enablingdesired backgrounds to be photographed with the subject, without theneed for painted backdrops, rear projection screens, etc. Further, bylocating the concave mirror as described above, vignetting is alleviatedin a simple and effective manner.

Although illustrative embodiments of the invention have been shown anddescribed, it is to be understood that various modifications andsubstitutions may be made by those skilled in the art without departingfrom the novel spirit and scope of the present invention.

What is claimed is:
 1. Apparatus for providing a photographed subjectwith selected backgrounds, the backgrounds being maintained on filmtransparencies, the apparatus having a housing with one portion thereofpositionable adjacent a camera lens, means carried by the housing forholding a film transparency, means carried by the housing forilluminating the film transparency, beam splitter means located withinthe housing, optical focusing means located in the housing between thefilm transparency and the beam splitter means, said illuminating meanslocated on the side of the film transparency opposite the side on whichthe focusing means is located, the improvement comprising, incombination:a concave mirror for alleviating vignetting located in thehousing on the side of the beam splitter means opposite the side onwhich the optical focusing means is located; said beam splitter meanshaving a partially reflective mirror surface; said beam splitter meansbeing positioned to permit the illuminated film transparency image topass through said beam splitter means, be reflected by said concavemirror back to said beam splitter means and be reflected from said beamsplitter means to the camera lens; and said optical focusing means beingpositioned and operative to produce an intermediate film transparencyimage in front of said concave mirror.
 2. Apparatus as described inclaim 1, said beam splitter means comprising a beam splitter cube inwhich the diagonal thereof is light-transmissive with a partiallyreflecting mirror surface.
 3. Apparatus as described in claim 1, saidbeam splitter means comprising an angled light-transmissive memberhaving a partially reflective mirror surface, the angle beingapproximately 45° with respect to the camera lens axis and extendingfrom below the camera lens and upwardly and away therefrom.
 4. Apparatusas described in claim 1, said optical focusing means comprising amovable lens system of positive power.
 5. Apparatus as described inclaim 1, said illuminating means comprising an incandescent lamp. 6.Apparatus as described in claim 1, said illuminating means comprising anelectronic flash synchronized with the shutter of the camera. 7.Apparatus as described in claim 1, said optical focusing meanscomprising a first cylindrical lens for reducing astigmatism and amovable lens system of positive power.
 8. Apparatus as described inclaim 1, including a mirror for reflecting the illuminated image fromthe optical focusing means through the beam splitter and to the concavemirror.
 9. Apparatus as described in claim 1, said concave mirrorcomprising a lens/mirror combination.
 10. Apparatus for providing aphotographed subject with selected backgrounds, the backgrounds beingmaintained on film transparencies, the apparatus having a housing withone portion thereof positionable adjacent a camera lens, means carriedby the housing for holding a film transparency, beam splitter meanslocated within the housing, optical focusing means located in thehousing between the film transparency and the beam splitter means, saidilluminating means located on the side of the film transparency oppositethe side on which the focusing means is located, the improvementcomprising, in combination:said beam splitter means comprising an angledlight-transmissive member having a partially reflective mirror surface,the angle being approximately 45° and extending from below the cameralens and upwardly and away therefrom; said optical focusing meanscomprising a movable lens system of positive power; a concave mirror foralleviating vignetting located in the housing on the side of the beamsplitter means opposite the side on which the otpical focusing means islocated; said beam splitter means being positioned to permit theilluminated film transparency image to pass through said beam splittermeans, be reflected by said concave mirror back to said beam splittermeans and be reflected from said beam splitter means to the camera lens,with the concave mirror being operative to focus the entrance pupil ofthe camera lens approximate the exit pupil of said optical focusingmeans; and said optical focusing means being positioned and operative toproduce an intermediate film transparency image in front of said concavemirror.
 11. Apparatus as described in claim 10, wherein said opticalfocusing means also includes a first cylindrical lens for reducingastigmatism.
 12. A method for alleviating vignetting from apparatus forproviding a photographed subject with selected backgrounds, thebackgrounds being maintained on film transparencies, the apparatushaving a housing with one portion thereof positionable adjacent a cameralens, means carried by the housing for holding a film transparency,means carried by the housing for illuminating the film transparency,beam splitter means located within the housing, optical focusing meanslocated in the housing between the film transparency and the beamsplitter means, the illuminating means located in the housing on theside of the film transparency opposite the side on which the focusingmeans is located, the steps comprising:locating said beam splitter meansat an angle of approximately 45° with respect to the axis of the cameralens and extending from below the camera lens and upwardly and awaytherefrom, with the beam splitter means comprising a light-transmissivemember having a partially reflective mirror surface; positioning aconcave mirror in the housing on the side of the beam splitter meansopposite the side on which the optical focusing means is located, sothat the concave mirror is operative to focus the entrance pupil of thecamera lens approximate the exit pupil of the optical focusing means;and positioning said optical focusing means to produce an intermediatefilm transparency image in front of the concave mirror.
 13. A method asdescribed in claim 12, including the further step of interposing anadditional mirror for reflecting the illuminated image from the opticalfocusing means through the beam splitter and to the concave mirror.